This invention concerns a coal slagging gasifier and more particularly to a quenching chamber arrangement thereof.
The coal slagging gasifier concerned is of the type (hereinafter call the type referred to) comprising a column-like gasifying vessel into which coal or other carbonaceous fuel is introduced into the top of the gasifying vessel and is gasified under high pressure and temperature by means of oxygen and steam introduced into the fuel in the gasifying vessel through tuyeres, and wherein residual ash collects as molten slag and iron in a hearth of the gasifying vessel from which said molten slag and iron are periodically discharged (commonly called `slag-tapping`) through a slag tap outlet in the hearth into water contained in a quenching chamber below the hearth, the pool of molten slag and iron being maintained in the hearth by hot combustion products passing up the slag tap outlet from burner means in or adjacent to the quench chamber to retain the slag and iron in the hearth, and tapping of the molten slag and iron being promoted by reducing pressure in the quenching chamber by controlled venting to atmosphere through a venting system so as to produce a differential pressure between the quenching chamber and the gasifying vessel.
A gasifier of the aforesaid type is disclosed in British Patent No. 1,512,677 in which the top end of the quenching chamber is formed by a relatively narrow neck, and the slag tap outlet has a lower end of bell-mouth shape opening into said neck. The aforesaid burner means is disposed around the wall of the bell-mouth, and a ring of nozzles emitting upwardly combustion sustaining gas is disposed in the quenching chamber just above the water level so that the combustion sustaining gas flows upwardly (towards the slag tap outlet) alongside the inner surface of the neck to help keep the latter cool. It has been found that fouling of the slag tap outlet and the burner means can occur. This appears to be due to excessive dribbling of slag and iron through the slag tap outlet between taps. These dribbles are broken into small fragments by the violent turbulence created in the quenching chamber by interaction between the flows of products of combustion from the burner means and the combustion sustaining gas from the ring of nozzles. These fragments are transported in the flows and deposited on various surfaces within the quenching chamber, for example the ring of nozzles and the burner means.
An object of the invention is to provide a gasifier of the type referred to capable of being constructed to avoid or reduce the chance of said fragments being deposited inconveniently.